Mycobacterium tuberculosis latently persist in 2 billion people, representing a major reservoir of tuberculosis (TB) due to reactivation, yet the state of latent bacilli remains a mystery. In order to eradicate TB, we need to understand latency and develop in vitro models for drug screening. In this interdisciplinary project we have merged microbiological tuberculosis research with nanotechnology and novel materials. Recent publications demonstrate a unique phenomenon of cell-directed assembly of hybrid lipid-inorganic nanostructures that drive a unique non-replicative persistence, and protect bacteria and drastically prolong viability. We show these same structures can be formed using mycobacteria, and that they display the highly extended viability characteristic of latency. We hypothesize that the persistence of latent TB, and its resistance to chemotherapeutic challenge, can be modeled by incorporation of bacilli into self-assembled lipid-inorganic nanostructures. This model combines the ability for in vitro study and growth condition modulation, with the potential for in vivo implantation and infection. We will generate a new in vitro model for high throughput screening for targets of, and drugs that can eliminate latent TB, to complement the existing complex in vivo models and al- low this field to move forward. Specific Aim 1 Define the conditions for optimal lipid-inorganic nanostructure-encasement of mycobacteria and its effects upon mycobacterial resistance to drugs. Specific Aim 2 Determine the changes in mycobacterial metabolism occurring upon encasement in lipid- inorganic nanostructures that result from non-replicative persistence, and drive in vitro survival and latency. Specific Aim 3 Demonstrate that lipid-inorganic nanostructure-encased mycobacteria represent valid models of latency by showing their infectivity in mice, even after extended periods of time after assembly. PUBLIC HEALTH RELEVANCE: Public Health Relevance We need to understand the way that tuberculosis is able to exist in a latent state because it is present in 2 billion people worldwide and reactivates into an active form in a significant percentage of cases. Clearing this 'reservoir'will be an essential component of an eventual eradication strategy. Although there are animal models of latency, there is no good model of in vitro latency, yet we need to have such an in vitro model so that we can understand how to attack it, and also to screen drugs with. We have developed a unique nanostructured model that mimics the extreme non-replicative persistence of latency, and want to test how effective it might be as a tool in the battle against TB.